UK police are contacting other forces worldwide in an attempt to close down websites with sexually violent content.

The move follows the murder of Brighton teacher Jane Longhurst by a man addicted to web porn.

Graham Coutts, 35, from Hove, had downloaded hundreds of images of asphyxia and necrophilia before he strangled Ms Longhurst last March.

Detectives have invited foreign law enforcement agencies to discuss ways of clearing the internet of such material.

BBC crime correspondent Neil Bennett said the police wanted more international co-operation - but they could have an uphill task.

"There's already what police call a global taskforce against child pornography... the judgements on other kinds of adult pornography are a bit more difficult, and much more difficult to regulate," he said.

Attitudes towards what kind of material should be illegal differ around the world, and the resources for policing it are insufficient in many countries, Bennett added.

BBC News Online technology correspondent Mark Ward said it would be almost impossible to stop such sites making their way onto the net.

"The problem is that even if you can get one ISP to take a site down, there is so much competition to host sites around the world that it will probably appear on another before long," he said.

'Fostered' fantasies

Peter Robbins, of the Internet Watch Foundation, agreed it is difficult to crack down on such sites unless they are based within the UK.
He told the BBC: "The type of information that this person (Coutts) was accessing has always been around, such as in book form."

And he added: "It is true the sex industry is making a great deal of money out of this (pornography on the internet)."

Coutts was sentenced to life imprisonment at Lewes Crown Court on Wednesday.

The trial heard that he had been surfing the net for images of dead and strangled women the day before luring Ms Longhurst, 31, to his flat on 14 March, and strangling her with a pair of tights.

He then kept her body for over a month - first in a shed and then at a storage unit - before setting fire to it in woodland in West Sussex.

He returned to the net after her body was found, five weeks after her death, and began searching for the same images again.

The prosecution said the internet had "fostered" his bizarre and macabre fantasies.

After the trial, Ms Longhurst's mother Liz, 72, urged the government to take action.

"I feel pressure should be brought to bear on
internet service providers to close down or filter out these pornographic sites, so that people like
Jane's killer may no longer feed their sick imaginations and do harm to others," she said.

Ms Longhurst's former partner Malcolm Sentance added: "Jane would still be here if it wasn't for the internet."